| 摘要 |
1482851 Drill shank ROBERT BOSCH GmbH 17 Jan 1975 [17 Jan 1974 22 Feb 1974] 2183/75 Heading B4C [Also in Division B3] The shank end 9 of a rotary tool, such as a masonry drill 5 is of multi-start helical spline form of helix angle jrom 75-85 degrees and directed so that when used in a tool holder with a complementarily formed socket, such as a receiving device 12 in holder 2 of a hand-held, rotary and percussive power drill 1, the torque reaction between the tool and the holder causes the tool to be axially urged into the holder and, as shown, against the percussion dolly 18. The spline may have six to ten teeth and the base width t 10 of the tool spline teeth 13, is in the ratio range of 1 : 2 to 3 : 4 relative to the base width of the spline teeth 14 in the receiving device 12. The shank end only, or the whole tool, may be made of plastics material or steel and formed by casting, extrusion moulding or injection moulding. Similarly, the device 12 may be of plastics or steel made by the same processes. |
